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ac3enc: merge compute_exp_strategy_ch() into compute_exp_strategy()

This commit is contained in:
Justin Ruggles 2011-04-15 22:43:25 -04:00
parent 4142487d1c
commit ba6bce5140
1 changed files with 33 additions and 42 deletions
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75
libavcodec/ac3enc.c
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@ -560,56 +560,47 @@ static void extract_exponents(AC3EncodeContext *s)
#define EXP_DIFF_THRESHOLD 500
/**
* Calculate exponent strategies for all blocks in a single channel.
*/
static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy,
uint8_t *exp)
{
int blk, blk1;
int exp_diff;
/* estimate if the exponent variation & decide if they should be
reused in the next frame */
exp_strategy[0] = EXP_NEW;
exp += AC3_MAX_COEFS;
for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
exp_diff = s->dsp.sad[0](NULL, exp, exp - AC3_MAX_COEFS, 16, 16);
if (exp_diff > EXP_DIFF_THRESHOLD)
exp_strategy[blk] = EXP_NEW;
else
exp_strategy[blk] = EXP_REUSE;
exp += AC3_MAX_COEFS;
}
/* now select the encoding strategy type : if exponents are often
recoded, we use a coarse encoding */
blk = 0;
while (blk < AC3_MAX_BLOCKS) {
blk1 = blk + 1;
while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
blk1++;
switch (blk1 - blk) {
case 1: exp_strategy[blk] = EXP_D45; break;
case 2:
case 3: exp_strategy[blk] = EXP_D25; break;
default: exp_strategy[blk] = EXP_D15; break;
}
blk = blk1;
}
}
/**
* Calculate exponent strategies for all channels.
* Array arrangement is reversed to simplify the per-channel calculation.
*/
static void compute_exp_strategy(AC3EncodeContext *s)
{
int ch, blk;
int ch, blk, blk1;
for (ch = 0; ch < s->fbw_channels; ch++) {
compute_exp_strategy_ch(s, s->exp_strategy[ch], s->blocks[0].exp[ch]);
uint8_t *exp_strategy = s->exp_strategy[ch];
uint8_t *exp = s->blocks[0].exp[ch];
int exp_diff;
/* estimate if the exponent variation & decide if they should be
reused in the next frame */
exp_strategy[0] = EXP_NEW;
exp += AC3_MAX_COEFS;
for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
exp_diff = s->dsp.sad[0](NULL, exp, exp - AC3_MAX_COEFS, 16, 16);
if (exp_diff > EXP_DIFF_THRESHOLD)
exp_strategy[blk] = EXP_NEW;
else
exp_strategy[blk] = EXP_REUSE;
exp += AC3_MAX_COEFS;
}
/* now select the encoding strategy type : if exponents are often
recoded, we use a coarse encoding */
blk = 0;
while (blk < AC3_MAX_BLOCKS) {
blk1 = blk + 1;
while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
blk1++;
switch (blk1 - blk) {
case 1: exp_strategy[blk] = EXP_D45; break;
case 2:
case 3: exp_strategy[blk] = EXP_D25; break;
default: exp_strategy[blk] = EXP_D15; break;
}
blk = blk1;
}
}
if (s->lfe_on) {
ch = s->lfe_channel;